The present invention relates to a drum for continuous cooling and separation of metallic castings from moulding sand forming previous casting moulds.
In known drum equipment designs used for this purpose, the general principle of heat exchange between the castings and moulding sand during their relative displacement in the drum is gainfully employed followed by evaporation of process water contained in the mass together with the water additionally introduced into the mass as well as withdrawal of steam outside the equipment. Cooling effected during such a process is accompanied by knocking out cores, crushing of the moulding sand, cleaning of castings, homogenization and dedusting of moulding sand. The existing structural designs are based on the use of a container revolving around a longitudinal horizontal or near horizontal axis. One of the bases is an inlet opening for introducing the moulding sand together with the castings. The outlet opening for castings is located on the other side of this container. A sieve wall for separation of the moulding sand is in the neighborhood of the outlet opening of the container over a determined segment there. Against the background of such a solution, several inventions have been devised aimed primarily at intensification of cooling of castings and moulding sand.
In the equipment presented in the French Patent No. 2,167,308, the cooling process is prolonged and also embraces the stage after separation of the moulding sand from the castings. The revolving container with the inlet and outlet openings exposed on both sides is enclosed with a coaxially connected jacket. The space between this jacket and the container is closed on the side of the inlet opening by means of a guard connected with an exhaust system. The side surface of the container shielded with the jacket is provided with a sieve wall. The end piece of the jacket is also made in the form of a sieve and is surrounded by a container for moulding sand. During the rotary motion of the container, the moulding sand is separated by the sieve wall, falls on the inner surface of the jacket, moves along this surface and after being sieved falls into the container. Air flow through the equipment initiated by suction action of the guard produces an inflow from both sides of the container that is through the inlet and outlet openings and then subsequently, through the meshes of the sieve wall of the container to a space encased in the jacket. Pouring of sand over a considerable length of the container shortens the time and reduces the intensity of heat abstraction from the castings to the moulding sand and, at the same time, limits the possibilities of introducing additional water. Main air streams flowing into the container do not pass directly above the pouring moulding sand and castings, but in the upper portions of the section of container, this being due to the fact that they are directed toward the exposed meshes of the sieve wall. This phenomenon reduces the intensity of evaporation of moisture and the efficiency of direct heat exchange. In order to obtain the final temperatures of the castings and moulding sand required, the equipment must have considerable dimensions.